This study, proposed by a multidisciplinary team of investigators who have substantial experience in personality, aging, and epidemiological studies, will be the first prospective, longitudinal study of the stability and impact of personality pathology in later life. It will examine connections among personality traits, personality disorders, health, and social adjustment in an out-of-treatment sample of persons between the ages of 55 and 64-those approaching the challenges of later life. It will identify the extent to which personality and personality disorders influence the ability to adapt successfully to important life transitions. Nosological comparisons will be made between two different approaches to the definition of personality pathology: the approach represented in DSM-IV and the Five Factor Model of personality. Consideration will also be given to the incremental validity of informant reports (relative to self-report measures) of normal and pathological personality traits in predicting adjustment problems. A representative sample of adults living in the St. Louis area (n=1,500) will be identified and recruited using random digit dialing. Baseline assessments to be completed by all participants will include a semi-structured diagnostic interview (SIDP-IV) and two questionnaires, the MAPP, and the NEO-PI-R. One informant per target (most often a spouse) will also complete the MAPP and NEO-PI-R to describe the participant's personality. Axis I disorders will be assessed using C-DIS screening modules for mood, anxiety, and substance use disorders. Approximately 15 to 20% of this sample is expected to exhibit significant features of personality disorders, broadly defined. A longitudinal design will include follow-up assessments of personality and personality disorders at regular, 2-year intervals. Follow-up assessments of social functioning and marital adjustment as well as physical and mental health (including depression) will be completed every 6 months. We will also monitor the occurrence of major life events and transitions. Data from this project will fill an important gap in current knowledge regarding the stability and course of personality disorders and elucidate their impact on health and social adjustment over the lifespan.